Method and apparatus for producing plastic bottles



May 8, 1962 J. B. WILLARD METHOD AND APPARATUS FOR PRODUCING PLASTICBOTTLES Original Filed Feb. 26, 1954 2 Sheets-Sheet 1 FIC3-2 INVENTORJOHN B- WILLARD q Y 8 AT TOR NEYS y 1962 J. B. WILLARD 3,032,809 METHODAND APPARATUS FOR PRODUCING PLASTIC BOTTLES 2 Sheets-Sheet 2 OriginalFiled Feb. 26, 1954 INVEN OR JOHN 5. WI LLARD ATTORNEYS United StatesPatent G 3,032,809 METHOD AND APPARATUS FOR PRODUCING PLASTIC BOTTLESJohn B. Willard, West Hartford, Conn, assignor, by mesne assignments, toOwens-Illinois Glass Company, Toledo, Ohio, a corporation of OhioContinuation of application Ser. No. 412,735, Feb. 26, 1954. Thisapplication May 16, 1960, Ser. No. 29,450 10 Claims. (Cl. 18-5) Thepresent invention relates to improvements in apparatus and process formanufacturing blown thermoplastic resin bottles and the like.

An object of the invention is to provide improved process and apparatuswherein a thermoplastic resin is extruded as a tubular stream from whicha bottle or the like is formed by press molding its neck and corkageportions and blow molding its body portion within a multisection mold.

A further object is to provide improved apparatus of the type indicatedin which the extruded resin is severed from its parent supply prior toblow molding the finished article.

With these and other objects in view, the invention consists of thehereinafter described method of operation and the novel combinations,constructions and arrangement of parts shown in the accompanyingdrawings of illustrative embodiments in which:

FIGURE 1 is a cross-sectional view of a tube of thermoplastic resinextruded from a nozzle into an open multisectional mold of a multi-moldmachine in accordance with the invention;

FIGURE 2 is a cross-sectional view similar to FIGURE 1 and showing themold closed on the plastic tube;

FIGURE 3 is a view similar to FIGURE 2 showing th tubing cut from thenozzle and with a mandrel projecting into the tubing from a blow head;

FIGURE 4 is a cross-sectional view taken on the line 4-4 of FIGURE 3showing the tube gripped by the closed mold and the plunger therein;

FIGURE 5 is a view similar to FIGURE 3 showing the bottle neckpress-molded between the plunger and pressing members;

FIGURE 5A shows a modification of the pinchers and plunger of FIGURE 5;

FIGURE 6 is a view similar to FIGURE 5 showing the tubing blow-molded toshape in the mold; and

FIGURE 7 is an elevation view of the blow-molded article from only oneside of which fiash has been removed.

Referring to FIGURES 1 and 2 of the drawings, there is shown anextrusion head or nozzle 1 having an annular outlet orifice 2 throughwhich a heated or otherwise plasticized and suitably homogenized organicplastic resin such as, for example, polyethylene is extruded in tubularform or shape 3. The extrusion head 1 may be stationarily mounted ormovably mounted as, for example, for vertical movement as disclosed inUS. Patent No. 2,349,176, issued May 16, 1944, to William H. Kopitke. Ineither case, it is contemplated that the head 1 be so disposed that moldsections 4a and 4b of a multi-section mold 4.may be brought intoregistry with the extrusion head 1.

In the embodiment illustrated in FIGURES 1-5, the mold sections 4a, 4bpreferably are mounted on a rotary turret table 5 which preferablycarries a plurality of equally spaced-apart molds (not shown) identicalwith mold 4.

As is hereinafter described in greater detail, the operation of themolds 4 may be automatically controlled in timed sequence with theoperation of the extruder head 3,032,809 Patented May 8, 1962 ICC 1 andother components of the apparatus by suitable timing mechanism (notshown).

The illustrated mold sections 4a and 4b form a mold cavity generallydesignated 9 (FIGURE 5) in which to blow mold and shape the plastictubing 3 into a bottle 10 (FIGURE 6).

In the embodiments shown in the drawings, the cavity 9 includes a mainbody molding portion 9a formed by the mold sections 4a, 4b, againstwhich the tubing 3 is blow molded and a neck molding portion 9b formedby a pair of neck shaping members 11a, 11b which are movable relative toeach other and in cooperation with a mandrel 6 serve to compression moldthe neck, corkage and finish portions 10a, 10b and 100, respectively, ofthe bottle 10 (FIGURE 7).

As shown in FIGURES 3 and 4, the portions of the mold sections 4a and 4babove the neck shaping members 11a, 11b are cut away at 12a and 12b,respectively, to provide a bore 12 which is adapted when the moldsections 4a, 4b are closed to grip and suspend in the molding cavity 9 alength of the tubing 3 which is severed from the nozzle 1 by a knife 15or other suitable means. The gripping bore 12 may be the same size oronly slightly smaller than the diameter of the tubing 3 and rely uponfriction to provide the desired support or, as shown in FIGURE 4, thebore 12 may be substantially smaller so that diametrically oppositeportions 3a and 3b of the tube 3 are pinched closed and gripped betweenthe mold sections 4a, 4b.

In either case an end of the length of the tube 3 within the mold 4remains open for the insertion of the mandrel 6 while the other end ofthe length of the tube 3 is closed as by pinching edges 13a, 13b on thebottom of the mold sections 4a, 4b, respectively.

While the mold 4 of the illustrated embodiments of the invention isshown upright, it is contemplated that the mold 4 may be inverted sothat the pinching edges 13a, 13b are located adjacent the nozzle 1 andprovide the suspending support for the length of tubing 3 within themold 4. In the latter case, the bore 12 need not support the length oftubing 3.

However, regardless of whether the bore 12 does or does not support thetubing 3 within the mold 4, the bore 12 does center and align the openend of the tubing to receive the mandrel 6.

As shown in FIGURE 3, the mandrel 6 extends downwarclly from a blowhead16 which is movable into and out of engagement with the top of the mold4. The movement of the blowhead 16 may be effected by any suitablemechanism. One such mechanism is illustrated and described in theaforesaid Patent 2,349,176.

Preferably the blowhead 16 makes substantially airtight engagement withthe top surface of the mold 4 and locates the mandrel 6 within theportion of the tubing 3 which is positioned between the neck shapingmembers 11a, 11b. The mandrel 6 may be rigidly secured to the head 16and movable into the tubing 3 as the. head 16 is moved into engagementwith the mold 4. Preferably, however, the mandrel 6 is movably journaledin the head 16 and is inserted in the tubing 3 from an exterior positionafter the blowhead 16 has been moved into engage- I ment with the mold4.

As shown in the drawings, the head 16 and mandrel which can engage andshape the adjacent end of the length L of tubing 3 into a lip portionfor the bottle rather than shaping the lip or finish as hereinafterdescribed,

As shown in FIGURE 5A, the lip or finish c of the bottle it is formed byan annular shoulder 6a of a modified mandrel 6'.

Alternatively, as shown in FIGURE 5, the mandrel 6 may form only theinner or corkage surface 10b of the bottle neck and the lip or finish100 may be formed by annular shoulder portions Ida, 18b of the members11a, 11b, respectively. A split mold seam is continued from the body andneck 10a of the bottle 10 over the lip or finish lttc in the embodimentshown in FIGURE 5 but is avoided by the continuous shoulder 6a of FIGURE5A.

In operating the forming apparatus shown in FIG URES l to 5, the rotaryturret 5 moves the open mold sections 4a, 45 into aligned rotaryregistry with the extrusion head 1 preparatory to the extrusion of apreselected length of tubing 3. Thereafter the preselected length oftubing 3 is extruded (FIGURE 1) and the mold sections 4a and 4b closedon the tubing, as shown in FIGURE 2 so that the bore 12 grips the top ofthe tubing while the pinching edges 13a, 13]) close the bottom of thetubing and form a bottom seam 21 for the bottle 10. Thereafter, theextruded tubing 3 is severed from the nozzle 1, as by operation of theknife 15, and the mold 4 moved, as by rotation of the turret 5, from itsstation in alignment with the nozzle 1 to a second station where theblowhead 16 is moved into engagement with the mold 4. Movement of themandrel 6 into the tubing 3, as shown in FIGURE 3, may be effectedeither concurrently or subsequently to the movement of the blowhead 16into contact with the mold 4. In either event, blowing air may beintroduced into the tubing 3 through passageway 7 in the mandrel so asto blow mold the bottle 10, as shown in FIGURE 6, either while or afterthe mandrel 6 is introduced into the tubing and moved to the positionshown in FIGURE 5. Preferably the members 11a, 11b are moved to theirneck molding positions shown in FIGURE 5 either just prior to orconcurrently with the introduction of blowing air into the tubing 3through the mandrel passage 7.

If the mandrel 6 is inserted in the tubing 3 prior to the closing of themembers 11a, 11b, the blowing air preferably is not introduced into thetubing until the members 11a, 11]). are closed on the upper portion ofthe tubing, as shown in FIGURE 5, and in combination with the mandrel 6press mold the neck and corkage of the bottle.

Preferably, the wall thickness of the tubing 3 is somewhat greater thanthe clearance between the molding walls of the neck molding members 11a,11b and the mandrel 6 so that the plastic resin may be firmly moldedinto thread portions or similar irregular depressions in the neckmolding cavity.

As shown in FIGURE 5, the molding members 11a, 1112 are cut away toprovide semi-circular cutting edges 21 which form a circular orificethattightly engages the mandrel 6 when the mold sections 11a, 11b areclosed so as to seal the mold cavity 9 closed and cause the annularshoulder portions 18a, 18b to mold the lip or finish 100 of the bottle10.

The cutting edges 21 (FIGURE 6) of the shoulders 18a, 18b virtuallysever any excess portion of the tubing- 3 that may extend above the lipforming shoulder. Anythin flash which may remain between the cuttingedge 21 and the mandrel 6 to connect the neck 10a of the bottle withexcess plastic material is readily broken after removal of the, bottle10 from the mold 4. Severance may be aided or completed by withdrawingthe mandrel 6 from the bottle 10 before opening the mold sections 4a,4b. Preferably, the withdrawal is effected with a rotary motion whichmay be imparted to the mandrel by a variety of means as, for example,threaded engagement of the mandrel 6 with the head 16.

In the modification shown in FIGURE 5A, it is contemplated that theslightly modified mold members 11a,

4 11b may be either open or closed prior to insertion of mandrel 6' intothe tubing 3.

In the latter case, if desired, the members 11a, 11b may be integralportions of the mold sections 4a, 4b, or immovably secured thereto.Following closing of the mold sections 4a, 4b, and 11a, 11b, mandrel 6which is tapered at its end for ready insertion into the tubing 3 isinserted and presses the tubing into shaping engagement with mold cavitywall so as to shape the exterior and interior Walls 10a and Iiib of theneck of the bottle ll The last portion of the inward movement of themandrel 6 shears the excess plastic 19 above the lip from the bottle It?as shown in FIGURE 5A.

The blowing air may be introduced into the bottle concurrently with orsubsequent to the inward movement of the mandrel 6 so as to assist inthe neck formation and resist the tendency of the inwardly movingmandrel 6 to drag the plastic out of the neck forming portion of themold. Generally, it will be found desirable to close the neck formingmembers 11a and 11b after the mandrel 6 has been introduced into thetube 3 and to initiating blowing only after the members 11a, 11b areclosed.

It will be apparent that the excess material 19 when detached from thebottle 10 may be readily removed as by a blast of air after retractionof the mandrel 6.

As soon as the mold sections 4a and 4b have closed, blowing air may beintroduced into the plastic bubble within the mold through the passage 7in the mandrel 6 and the turret 5 may be rotated to remove the mold 4from beneath the extrusion head 1 so that one or more like molds (notshown) carried by the turret 5 may be successively positioned beneaththe head 11 to repeat the extrusion and mold closing operations. Inorder to achieve optimum etiiciency, the blowing operation may becommenced or continued at succeeding positions of the mold 4 and thebottle 10, or other molded article removed at a position just prior toagain positioning the mold 4 beneath the extrusion head 1.

The passage 7 which extends downwardly through the mandrels 6 and 6'communicates with an air pressure supply line (not shown). Thecommunication may be continually maintained and air pressure suppliedintermittently, as by means of a timer valve (not shown) or, forexample, the communication of the supply with the passage 7 may beeffected only when the mandrels 6 and 6' are moving towards or are intheir lower or advanced positions shown in FIGURES 5 and 5A. It will beunderstood that the means for intermittently supplying air pressurethrough the passage 7 in the mandrels are merely illustrative and that awide variety of alternatives may be employed to properly time andcoordinate the air thus supplied with the several operations of theplastic blowing and molding apparatus.

This application is a continuation of my co-pending application SerialNumber 412,735 filed February 26, 1954 and now abandoned.

Having thus described the invention, I claim:

.1. The method of forming a hollow article of plastic material whichcomprises extruding tubular plastic material downwardly from an annularorifice, severing a length of tubular material from the materialextruding from the orifice to leave the severed end of said length openand gripping the exterior of the upper end of said length of tubularmaterial adjacent its severed end with said end.

remaining open, thereafter inserting av mandrel, into the upper open endof the gripped length of tubular material, press molding against themandrel a portion of said length adjacent said severed end, independentof the gripping of the exterior of the upper end of said length, andblow molding another portion of the length of tubular material with thelower end of said length of tubular material closed.

2. The method of forming a hollow article of plastic material whichcomprises extruding tubular plastic ma- 7 terial downwardly from anannular orifice, severing a length of tubular material from the materialextruding from the orifice to leave the severed end of said length open,supporting said open ended, severed length of tubular material within amold, with one end portion of said length being peripherally restrainedby an article portion forming section of said mold advancing a mandrelinto the open end of said one end portion of said supported length oftubular material, While restraining said mold against lateral movementaway from said mandrel whereby said one end portion of said length oftubular material is press molded between said advancing mandrel and saidarticle portion forming section of said restrained mold, and blowmolding another portion of the length of tubular material with the otherend of said length of tubular material closed.

3. The method recited in claim 2 and wherein the advancing mandrelcooperates with the mold to shear excess material from the severed endof the press-molded portion of the length of plastic material.

4-. Apparatus for forming a hollow article of plastic materialcomprising a downwardly directed annular extruder nozzle or extruding atubular length of plastic material, means for severing a length ofextruding tubular material from the material extruding from said nozzleto leave the severed end of said length open, a sectional mold, meansfor gripping the exterior of the upper end of said length of tubularmaterial adjacent its severed end with said end remaining open tosuspend said length within said mold, a mandrel mounted to be movableinto the upper open end of the gripped length of tubular material, meansfor inserting said mandrel into the upper open end of the gripped lengthof tubular material, pinch means movably mounted independently of saidgripping means and the sections of said mold to be movable into pressmolding cooperation with said mandrel to press mold a portion of saidlength of tubular material adjacent the uppensevered end thereof, andmeans for blow molding another portion of the length of tubular materialwithin said sectional mold.

5. Apparatus as recited in claim 4 and wherein said mandrel has anannular shoulder which cooperates with the press molding pinch means tosever the severed end of the tubular length from the press-moldedportion.

6. The method of forming a hollow plastic container having a neckcomprising the steps of disposing a tubular formation of heatedthermoplastic material between the opened halves of a partiblecontainer-defining mold, closing said mold halves on said tubularformation in such manner that the end of the tubular formation adjacentthe neck forming portions of the partible mold remains open, and isperipherally restrained by said neck forming mold portions, pressmolding the neck portion of the container by inserting a mandrel intosaid peripherally restrained open end of said tubular formation, andexpanding the remainder of the mold enclosed portions of the tubularformation to conform to the mold cavity by fluid pressure introducedthrough said mandrel.

7. The method of forming a hollow article of plastic material whichcomprises extruding tubular plastic material downwardly from an annularorifice, gripping a length of said tubular material, simultaneouslysevering the gripped length from the oncoming extrusion in such manneras to leave the severed ends open, relatively moving the gripped lengthand the orifice, thereafter inserting a mandrel into an open andperipherally restrained end of the gripped length to press mold anarticle portion defining section of the gripped length around saidmandrel, and blow molding another portion of the gripped length.

8. The method of forming a hollow plastic container as recited in claim6 wherein as said mandrel is inserted into said open end of said tubularformation to press mold the neck portion of said container, fluid isintroduced through the mandrel.

9. The method of forming a hollow article of plastic material as recitedin claim 2 wherein said mandrel is advanced into the upper open end ofsaid supported length of tubular plastic material and wherein the blowmolding of another portion of said length of material is effected withthe lower end of said length closed.

10. The method of forming a hollow article of plastic material asrecited in claim 7, said article being a container having a threadedneck and a body, wherein a blow mold defining the complete container isclosed onto the length of tubular material, the mandrel is inesrted intothe open end of said length peripherally restrained by a first, threadedportion of the blow mold defining the container threaded neck, and theremaining portions of said length are subsequently blow molded against asecond portion of the blow mold defining the container body.

References Cited in the file of this patent UNITED STATES PATENTS2,783,503 Sherman Mar. 5, 1957 2,810,934 Bailey Oct. 29, 1957 2,898,633Burch Aug. 11, 1959 2,903,740 Parfrey Sept. 15, 1959 FOREIGN PATENTS1,029,586 France June 3, 1953

